Car-lighting system



H. D. ROHMAN.

CAR LIGHTING SYSTEM.

APPLICATION FILED APR. 23. 1917.

1,351,788. PatentedSept. 7,1920.

" l i l hl l i l l l l MFA/E65:

HARRY D. IROHMAN, OF NEW YORK, N. Y.,

PATENT OFFICE.

ASSIGNOR, BY MESNE ASSIGNMENTS, TO J.

STONE & COMPANY, LIMITED, OF DEPTFORD, ENGLAND.

CAB-LIGHTING SYSTEM.

Specification of Letters Patent.

Patented Sept. 7, 1920.

Application filed April 23, 1917. Serial No. 163,815.

To all whom it may concern:

Be it known that I, HARRY D. RoHMAN, a citizen of the Republic of Switzerland, residing at New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Car-Lighting Systems of which the following is a specification.

This invention relates to electric lighting and heating systems such as used on railway and other vehicles and it has for one of its primary objects the provision of improved means for maintaining proper voltage regulation on the work circuit, such for example as a bank or banks of lamps, particularly during the operation of cutting in and cutting out, that is to say, at the time when the load is transferred from the battery to the dynamo and vice versa.

My invention also resides in utilizing the automatic cut-in and out switch for effecting this regulation. Another object of the invention resides in the provision of an improved system whereby the lamp load at the moment of cutting out can be taken up by the battery in such manner that if the battery has a comparatively high gassing voltage, the increase in the lamp voltage due to this comparatively high gassing voltage will be gradual and not perceptible.

My invention is also particularly useful in connection with train lighting systems employing a single unit battery, as'will further appear, although capable of use equally well on double battery equipments.

I accomplish the foregoing and such other objects as may hereinafter appear, by means of an improved system illustrated in the accompanying drawings, wherein Figure 1 is a diagram of the system; and Figs. 2 and 3 are sectional views of details employed in carrying out my invention.

My invention will be described as applied to a single battery system. The battery A is supplied by a dynamo B suitably drlven from a car axle in any well known manner, the dynamo being preferably of the slipping belt type, in which the armature rotates at a substantially uniform rate of speed after the train reaches a rate of speed, say for example 15 miles per hour, at which speed the dynamo is constructed to deliver full output. The numeral 8 denotes the positive lead from the dynamo to the battery and to the group or groups of lamps or other translating devices C, while the reference numeral 9 denotes a common return lead. Located in the positive lead 8 is an automatic cut-in and out switch D of a type particularly sensitive and gradual in operation, such switch being provided with a shunt coil 10 and a series coil 11,.the switch being so arranged that when the dynamo develops a voltage equal to or greater than that of the battery, the cut-in switch will close, and will open when the dynamo voltage drops below that of the battery. The reference numeral 12 indicates the lamp switch.

Heretofore in train lighting systems employing a generator and a battery to supply the lamps, the generator being used both to supply the lamps and to charge the battery, it has been customary to provide a main lamp resistance which is effective when the dynamo is supplying the lamps and is charging the batteries, in order that the voltage of the work circuit would be maintained within proper limits. In such systems when the dynamo cuts out, and the battery takes up the lamp load, the resistance is short circuited, this usually being effected through the instrumentality of the cut-in switch. This main lamp resistance is proportioned or calibrated so as to accommodate itself to wide variations in dynamo output, and this results in difficulties, particularly in single battery equipments, as will be apparent from the following: In such a system, assuming that the lamp load is directly across the battery, say at 32 volts, the cut-in switch closes when the dynamo develops a voltage equal to that of the battery, and then the dynamo begins to supply the battery and at the same time take up the lamp load. Since, however, the dynamo current must pass through the main lamp resistance, there is a marked drop in voltage in the lamp circuit, at the moment the cut-in switch closes. The main lamp resistances are, usually so calibrated that there is a drop of about 8 volts across the resistance, from which it will be readily seen that at the moment of cut-in, when the dynamo assumes the lamp load, the voltage in the lamp circuit will drop in an amount corresponding to the drop across the resistance, this change being marked by a decided flicker on the lamps. Again, it will be noted that when the automatic cut-in switch opens, and short circuits the main lam resistance, the battery takes up the load 0 the lamps, and

this cannot be done with this general type of system without causing a serious flicker on the lamps.

It is the purpose of my invention to overcome these difliculties so that the change from battery to dynamo and vice versa will be accomplished without substantial change Y 32 volts.

in voltage on the lamp circuit, and consequently without flickering of the lights. I accomplish the foregoing in the following manner:

T locate in the positive lead 8, on the lamp side of the cut-in switch, a high positive temperature coefficient resistance 13, such resistance also being located beyond the point from which the battery A is supplied from the dynamo. This resistance is so calibrated that the drop across it-is about 8 volts. Four flexible brushes, 1, 2, 3, and 4, are suitably mounted on the frame 14 of the cut-in switch D, and insulated there-v from, such brushes being adapted to be engaged successively by pins, 1*, 2*, 3, and 4, carried on the bar 15 which in turn is carried on the stem 16 of the core of the cut-in switch. All of the brushes are in electrical connection at one end with the positive 8 and are adapted to make contact at the other end with respective contacts 1", 2 3", and 4'. Contact 1 is connected to the positive of the lamps by means of wire 17 and wire 18; contact 2 is connected to wire 18 through the medium of resistance 2; contact 3 is connected to wire 18 through the medium of resistance 3; and contact 4 is connected to wire 18 through the medium of resistance 4. When the cut-in switch is open all of the brushes 1, 2, 3, and 4, are maintained in wiping contact with their respective contacts by the yoke 19 carried on the bar 15, as will appear from an inspection of Figs. 2 and 3.

It will be seen from the foregoing arrangement that when the cut-in switch is open, there is a direct path from the battery A to the lamps C through brush 1, contact 1*, wire 17 and wire 18, while resistances 2, 3, 4, and 13 are connectedin parallel. The automatic cut-in switch is so calibrated as to sensitively and gradually respond to fluctuations in voltage and current.

The operation is as follows, assuming that the lamps are lighted and the cut-in switch is open, the lamps being directly across the battery at a potential, say for example, of Assuming that the train starts, the generator begins to build up and at 32 volts the automatic switch D connects the generator and the battery and the lamp load is carried by the dynamo, with the battery floating on the lamps. With an increase in output, the plunger of the cut'in switch will rise slightly, breaking the circuit of brush 1, thus severing the direct connection between the battery and the lamps. This first initial movement of the cut-in switch takes place when the dynamo voltage or the pressure in the system rises about 2 volts. T he dynamo now supplies the lamps through resistances 2, 3, 4, and 13, which resistances are in parallel, the resistances 2, 3, and 4 being so calibrated that there is a drop of-2 volts across such resistances. This ldrop across the resistances in parallel compensates for the rise in voltage in the dynamo, and thus, the voltage on the lamp circuit is still maintained at 32 volts, although in the meantime, the battery voltage will rise.

Upon a still further increase in dynamo output, and an increase, say of 2 volts in the circuit, the cut-in switch plunger will be raised still further to a point when it will lift up the brush 2 and sever the connection for resistance 2, thus leaving resistances 3, 4, and 13 in parallel. The total resistance is thus increased, or stated in other words, the conductivity is reduced so that there is a drop of about 4volts across the resistances. This increased drop compensates for the in crease in voltage, and as a result of which the voltage on the lamps will still remain substantially at 32 volts.

By this time the battery may have reached 36 or 37 volts and the positive temperature coeflicient 13 is beginning to take up part of the load by its becoming heated, such re- 'sistance therefore providing a fairly wide range of regulation.

l pon further increase in pressure, the resistance 3 will be cut out, leaving resistance 4 and resistance 13 in parallel, with the ef fect previously described; and upon an additional increase, resistance 4 may be cut out, leaving only the main lamp resistance 13, which is capable of amply compensating for additional variations in pressure because -of increase in its temperature, the net result being that lamp voltage is maintained at substantially the same figure without flickering, notwithstanding the voltage in the system may increase to a maximum point corresponding to full charge conditions.

It will alsobe observed that the arrangement is such as to be particularly advantageous when, for any reason, such as slowing up of the train, the dynamo voltage begins. to drop. lVhen this occurs it will be noted that the downward movement of the core of the cut-in switch is gradual, asbefore, with the result that the resistances are .successively placed in parallel, thus succesbattery as the cut-in switch begins to de scend, and a large portion of this excess high voltage is utilized before the cut-in switch actually opens, the net result being that the transfer to the battery is gradually accomplished without any flicker on the lamps, which would otherwise result because of the high gassing voltage.

It will be seen from the foregoing that I have provided a simple and effective means for maintaining proper lamp voltage regulation. lVhile I have illustrated but one group of lamps, it will of course be understood that the system isapplied where there are several circuits, and if desired, the supplementary resistances ma be of the inductive type so that their e ect when placed in parallel will be gradual.

Any type of cut-in switch suitable for the purpose of the present invention may be employed, but I prefer that shown in Fig. 2, the same being in all substantial respects similar to that shown and described in my copending application, Serial Number 82,834, filed March 6, 1916, it being understood in this connection that the lower brush which completes the generator ositive has sufiicient flexibility to permit 0 the operation described.

I claim: 4

1. In a car lighting system, the combination of a dynamo, a battery, translating devices, a positive lead from the dynamo to the translating devices, a main resistance in said positive, a positive battery lead connected tothe dynamo positive intermediate the dynamo and said main resistance, a plurality of secondary resistances connected to the dynamo positive intermediate said main resistance and the translating devices and adapted to be connected to the dynamo positive intermediate the dynamo and the point of connection of the battery positive to the dynamo positive, and an automatic switch adapted to successively complete and disconnect the circuits for said secondary resistances.

2. In a car lighting system, the combination of a dynamo, a battery, translating devices, a positive lead from the dynamo to the translating devices, a main resistance in said positive, a positive battery lead connected to the dynamo positive intermediate the dynamo and said main resistance, a plurality of secondary resitances connected to the dynamo positive intermediate said main resistance and thetranslating devices and adapted to be connected to the dynamo positive intermediate the dynamo and the point of connection of the battery positive to the dynamo positive, and an automatic cut-in switch adapted to successively complete and disconnect the circuits for said secondary resistances.

3. In a car lighting system, the combination of a dynamo, a battery, translating devices, a positive lead from the dynamo to the translating devices, a main resistance in said positive, a positive battery lead connected to the dynamo positive intermediate the dynamo and said main resistance, a plurality of secondary resistances connected to the dynamo positive intermediate said main resistance and the translating devices and adapted to be connected to the dynamo positive intermediate the dynamo and the point of connection of the battery positive to the dynamo positive, and an automatic cut-in switch adapted to successively complete and disconnect the circuits for said secondary resistances, together with means operated by the automatic cut-in switch adapted to directly connect the translating devices across the battery when the cut-in switch is open.

4. In a car lighting system, the combination of a dynamo, a battery, translating devices, a cut-in switch, and a plurality of resistances between the dynamo and the translating devices, said resistances being arranged to be connected in parallel and to be successively disconnected by the cutin switch as it closes and to be successively con nected by said switch it opens as and for the purpose set forth.

In testimony whereof I have hereunto signed my name,

H. D. ROHMAN. 

